The door to heel is a field of natural gas in Darweza, Turkmenistan which was discovered in 1971. It is in the middle of the Karakum Desert, about 260 kilometres (160 mi) north ofAshgabat. The gas reserve found here is one of the largest in the world. The name "Door to Hell" was given to the field by the locals, referring to the fire, boiling mud, and orange flames in the large crater, which has a diameter of 70 metres (230 ft). The hot spots range over an area with a width of 60 metres (200 ft) and to a depth of about 20 metres (66 ft).

The site was identified by Soviet engineers in 1971. It was originally thought to be a substantial oil field site. The engineers set up a drilling rig and camp nearby, and started drilling operations to assess the quantity of oil available at the site. When they instead found gas, the ground beneath the drilling rig and camp collapsed into a wide crater and disappeared.

Expecting dangerous releases of poisonous gases from the cavern into the nearby towns, the engineers saw it as best to burn the gas off. The gas was estimated to burn out within a few weeks, but it has instead continued to burn for more than four decades after it was set on fire.

In April 2010 the country's president, Gurbanguly Berdimuhamedow, visited the site and ordered that the hole should be closed but this is yet to happen. The Karakum Desert, which covers much of Turkmenistan, lies east of the Caspian Sea. The Aral Sea is located to the north and the Amu Darya river and the Kyzyl Kum Desert lie to the north-east. The area has significant oil and natural gas deposits. Turkmenistan plans to increase its production of natural gas, intending to increase its export of gas to many countries for example Pakistan, China, India, Iran, Russia, and Western Europe from its present level to 75 million cubic metres (2.6×109 cubic ft) in the next 20 years.